/*
 * Copyright 1999-2012 Alibaba Group.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package com.alibaba.cobar.mysql;

import java.security.DigestException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * 加密解密工具类
 * 
 * @author xianmao.hexm 2010-4-14 下午03:22:05
 */
public class SecurityUtil {

  private static final int CACHING_SHA2_DIGEST_LENGTH = 32;

  public static byte[] scrambleCachingSha2(byte[] password, byte[] seed) throws DigestException {
    MessageDigest md;
    try {
      md = MessageDigest.getInstance("SHA-256");
    } catch (NoSuchAlgorithmException ex) {
      throw new DigestException(ex);
    }

    byte[] dig1 = new byte[CACHING_SHA2_DIGEST_LENGTH];
    byte[] dig2 = new byte[CACHING_SHA2_DIGEST_LENGTH];
    byte[] scramble1 = new byte[CACHING_SHA2_DIGEST_LENGTH];

    // SHA2(src) => digest_stage1
    md.update(password, 0, password.length);
    md.digest(dig1, 0, CACHING_SHA2_DIGEST_LENGTH);
    md.reset();

    // SHA2(digest_stage1) => digest_stage2
    md.update(dig1, 0, dig1.length);
    md.digest(dig2, 0, CACHING_SHA2_DIGEST_LENGTH);
    md.reset();

    // SHA2(digest_stage2, m_rnd) => scramble_stage1
    md.update(dig2, 0, dig1.length);
    md.update(seed, 0, seed.length);
    md.digest(scramble1, 0, CACHING_SHA2_DIGEST_LENGTH);

    // XOR(digest_stage1, scramble_stage1) => scramble
    byte[] mysqlScrambleBuff = new byte[CACHING_SHA2_DIGEST_LENGTH];
    xorString(dig1, mysqlScrambleBuff, scramble1, CACHING_SHA2_DIGEST_LENGTH);

    return mysqlScrambleBuff;
  }

  public static final byte[] scramble411(byte[] pass, byte[] seed) throws NoSuchAlgorithmException {
    MessageDigest md = MessageDigest.getInstance("SHA-1");
    byte[] pass1 = md.digest(pass);
    md.reset();
    byte[] pass2 = md.digest(pass1);
    md.reset();
    md.update(seed);
    byte[] pass3 = md.digest(pass2);
    for (int i = 0; i < pass3.length; i++) {
      pass3[i] = (byte) (pass3[i] ^ pass1[i]);
    }
    return pass3;
  }

  public static final String scramble323(String pass, String seed) {
    if ((pass == null) || (pass.length() == 0)) {
      return pass;
    }
    byte b;
    double d;
    long[] pw = hash(seed);
    long[] msg = hash(pass);
    long max = 0x3fffffffL;
    long seed1 = (pw[0] ^ msg[0]) % max;
    long seed2 = (pw[1] ^ msg[1]) % max;
    char[] chars = new char[seed.length()];
    for (int i = 0; i < seed.length(); i++) {
      seed1 = ((seed1 * 3) + seed2) % max;
      seed2 = (seed1 + seed2 + 33) % max;
      d = (double) seed1 / (double) max;
      b = (byte) java.lang.Math.floor((d * 31) + 64);
      chars[i] = (char) b;
    }
    seed1 = ((seed1 * 3) + seed2) % max;
    seed2 = (seed1 + seed2 + 33) % max;
    d = (double) seed1 / (double) max;
    b = (byte) java.lang.Math.floor(d * 31);
    for (int i = 0; i < seed.length(); i++) {
      chars[i] ^= (char) b;
    }
    return new String(chars);
  }

  private static long[] hash(String src) {
    long nr = 1345345333L;
    long add = 7;
    long nr2 = 0x12345671L;
    long tmp;
    for (int i = 0; i < src.length(); ++i) {
      switch (src.charAt(i)) {
        case ' ':
        case '\t':
          continue;
        default:
          tmp = (0xff & src.charAt(i));
          nr ^= ((((nr & 63) + add) * tmp) + (nr << 8));
          nr2 += ((nr2 << 8) ^ nr);
          add += tmp;
      }
    }
    long[] result = new long[2];
    result[0] = nr & 0x7fffffffL;
    result[1] = nr2 & 0x7fffffffL;
    return result;
  }

  private static void xorString(byte[] from, byte[] to, byte[] scramble, int length) {
    int pos = 0;
    int scrambleLength = scramble.length;
    while (pos < length) {
      to[pos] = (byte) (from[pos] ^ scramble[pos % scrambleLength]);
      pos++;
    }
  }

}
